murmurs ] hey! ♪ [ howls ] ♪ >>> remembering the victims of the violence here inboston.krystlecampbell, martinrichard, lingzi lu all three killed at the finish line of the boston marathon and officer sean collier shot and killed thursday night while police searched for the suspects. >>> and police officers and firefighters from all around the boston area saluted officer collier as a hearse drove his body to a funeral home yesterday. police say it's not clear why one of the suspects shot and killed him. but collier had been responding to a loud disturbance at the time. the 26-year-old had been a police officer for just over a year. >> and new details are trickling in this morning about the bombing suspects and possible ties to islamic extremism. cnn foreign affairs correspondent jill dougherty at the white house this morning. jill, you are also moscow bureau chief for nine years. you are very familiar with russia. what more do we know about the investigation into the older brother's behavior? >> okay. so that would have been the older brother of course is tamerlan tsarnaev. and we have